Occult blood in faeces linked with all-cause mortality

By Melanie Hinze
The presence of detectable faecal haemoglobin may be associated with an increased risk of death from a range of causes, in addition to colorectal cancer (CRC), according to research published in Gut.

Researchers investigated all 134,192 people from the guaiac faecal occult blood test (gFOBT) screening in Tayside, Scotland, between March 2000 and March 2016, then linked gFOBT test results with mortality data from the National Records of Scotland database.

They found that people with a positive test result (n=2714) had a higher risk of dying from CRC than those with a negative result after adjusting for sex, age, deprivation quintile and medication that can cause bleeding. 

Interestingly, a positive result was also significantly associated with an increased risk of dying from circulatory, respiratory, neuropsychological, blood and endocrine disease, digestive diseases excluding CRC and other cancers. 

Professor Finlay Macrae, Head of Colorectal Medicine and Genetics at the Royal Melbourne Hospital, commented that the increased mortality from CRC in those with a positive gFOBT was easily understood and explained, as the researchers described. 

‘What is more interesting is the increased non-CRC mortality in the positive versus the negative group,’ he said.

While the authors suggest that a generalised inflammatory state manifested by subclinical colonic inflammation might account for this observation, Professor Macrae said he would like to see more detail on the non-CRC causes of death and suggested there may be other explanations.

‘For circulatory disease, there would be ischaemic gut. There would be patients undergoing CRC operations but who die of respiratory disease in the postoperative period. For neuropsychological disease, there may be suicides induced by the disclosure of a positive FOBT. For other digestive diseases, there are a host of GI conditions that bleed and may be fatal. Finally, for blood diseases, there may be coagulation issues leading to positive FOBT but ultimately being the cause of death,’ he said.

Despite this, Professor Macrae told Medicine Today this was an interesting outcome study that called for further studies which may confirm these observations. 
Gut 2018; doi: 10.1136/gutjnl-2018-316483.